Embodiments of this invention generally relate to an elevator system, and more particularly, to an elevator system that employs dynamic braking.
Dynamic braking is a technique used to slow a motor through the use of back electromotive force (emf). Generally, dynamic braking operates by shorting terminals of a permanent magnetic machine, allowing the back emf to resist rotation of the rotor. Dynamic braking is used in a wide variety of applications. Exemplary existing systems use switchover relays and power resistors to connect motor leads together in a star connection. This type of design is used in systems where a DC power source remains charged at all times. Such systems require extremely high cost relays to handle the currents generated by the active DC source. Another exemplary existing design uses power resistors to short the DC power source rather than the motor windings.